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How to Drill Through Stainless Steel

August 30th, 2012

posted by AutoDrill

Drilling through stainless steel is much like drilling through any other type of metal but with a few key differences.

Using high-speed drill bits or better is mandatory. There are also other steps to drilling this material that will make the process easier. Many people have drilled holes into plain old steel with satisfactory results. Although drilling through stainless steel is different from drilling mild steel, the basic technique is much the same. Here’s how to get those holes drilled without ruining “drill bits”
Things You’ll Need

Variable speed power drill

Eye protection

See below for misc. items

Basic Instructions

First… Is there anything that could get caught in the drill such as loose clothing or hair? Are you wearing gloves? (don’t!) Safety first…

Second… Make sure that whatever you are drilling into is placed in a place that cannot be damaged as the drill passes through the part. As one person put it, don’t put it in your lap and drill down towards your leg! Duh!!!

Hold it secure! Clamping the part down is critical. If it is not properly clamped down, you may see it move, spin, or even lift up causing damage or even injury while drilling.

“X” marks the spot. Locate the exact spot where you want the hole and mark it with a permanent marker or even use a center punch to mark the location. Use heavy-duty tape to mask the area around your mark if you are worried about the chips scratching the surface as they spin. The best way, by far is to use the center punch to make a sharp depression in the metal. Holding the punch firmly on your mark, rap it sharply with your hammer once or twice to set the tiny puncture. Make sure it does not move between the hammer blows. This will prevent the drill bit from sliding away from your target as you drill.

DO NOT DRILL YET, but if the hole is larger than 3/8″ diameter or 8mm, use a two-bit process. Unless you have a drill press, hand drilling in metal is most easily done with a two-step process when you go above those sizes. To begin, install a “drill bit” roughly half the size of the hole diameter you need. For example, if you need a 1/2″ hole, start with a 1/4″ inch bit. Once you have drilled the 1/4″ hole, install your 1/2″ bit and drill again to finish the job. Thinner metal, for example less than 1/8-inch thick, may allow the use of a single bit to accomplish the task but has a much higher risk of “grabbing” as the tool breaks through the material. The “drill bit” turns into a screw-like device.

Put several drops of lubricating oil into the depression you made with the center punch. With eye protection on and hearing protection in place, hold your drill perpendicular to the bracket, insert the tip of the bit into the punched hole and begin to drill.

Slowly pull the trigger until the bit gains rotational speed being careful to keep it on target. Ultimately, the drill bit will win the contest and you’ll have bored that hole. Switch bits and begin again if needed to finish off the final hole. Add more lubrication often. Stainless does not conduct hear well so the tip of the “drill bit” will get very hot, very quickly.

Clean it up. Once you’ve drilled the hole, wipe off the excess lubricating oil with a rag. As you do, you’ll notice that the back of the bracket is fairly rough. Using a metal file, take down the ragged edges of the hole being careful not to damage the bracket. If necessary, apply more heavy-duty tape to mask the area.

BONUS TIP: By using an even larger drill bit, you can de-burr the hole on both sides if desired.

Consider using some sort of plastic or felt on your clamp if the surface will be easily damaged.

Drill slowly and allow the bit to do the work. Some will tell you that if you apply too much pressure, friction will cause your drill bit to redden with heat which will ruin it or your piece of stainless steel. If you are spinning slow enough and have enough lubrication, then this will not happen. In fact, more pressure can sometimes cause the drill to stay cooler as it travels through virgin metal below the last cut surface on every rotation. Let off on the pressure as you break through to avoid spiraling into the hole.

Overheating the tool can happen if you engage the drill to its full speed. The trick here is to find a happy medium, that “sweet spot” at which the drill, the bit and the metal cooperate fully. If it appears there’s too much smoke from the lubrication, back off immediately. Allow the bracket to cool for a few minutes and start the process again. You’ll save the “drill bit” in the process. When in doubt, drill slower. Also, the larger the hole diameter, the slower you should spin the “drill bit” to reduce heat.

Once you’ve removed shards and burrs, you can sometimes finish smoothing the area with steel wool as long as the marks left by the process are desirable.

Eye protection is a must! Work safe!!!

Don’t touch the bracket or the drill bit with your bare hand until they have cooled.